Method of forming transformer-core lamine



April 28, 1931. E. J. DOYLE 1,802,502

METHOD OF FORMING TRANSFORMER CORE LAMINAE Filed Oct. 1.4. 1 29 jzg 119 Patented Apr. 28, 1931 TA'EES PATIENT oFFieE EDWARD J. DOYLE, OF CHICAGO, ILLINOIS, ASSIGNOR TO TRANSFORMER CORPORATION OF AMERICA, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS METHOD OF FORMING TRANSFORMER-CORE LAMINE Application filed October 4, 1929. Serial No. 397,227.

This invention relates to a method of die punching and particularly to a ,method of making core laminations for electrical apparatus.

Certain forms of electrical apparatus, such as transformers and the like, utilize cores made from laminations assembled from E and I pieces, which, when assembled, consist of parallel bases with three parallel legs or tongue members to form parallel slots to receive the core winding. Every layer or complete lamination comprises a set including an E piece or member and an I piece, which I piece is positioned across the ends of the tongues to connect the same and enclose the core winding slots, thus making a core which is substantially rectangular in outline.

An object of this invention is to provide a method of forming or cutting E and I core lamination pieces from a long, relatively narrow strip of suitable metal in such manner that the laminations will be cut on all margins uniformly and cleanly and with minimum waste of material and which laminations will be ready for assembly without further work on the same.

According to the invention, the method contemplates punching the necessary holes,

then cutting out an E piece from substan tially half the width of the strip, with the legs or tongues of the E piece extending transversely of the strip and leave two oblong lateral projections on the opposite half of the strip then remaining; then cutting out the I pieces, which include the two lateral projections just mentioned, and then simultaneously forming an E piece by cutting out the I pieces. which E piece is then severed from the strip and trimmed along its back edge.

The accompanying drawings illustrate dies suitable for carrying out the method of this invention and also illustrate the several operations involved, and the views thereof are as follows:

Figure 1 is a bottom plan view of the upper or male die member.

Figure 2 is a top plan view of the lower or female die member.

Figure 3 is a plan View of a pair of I pieces formed in accordance with the method of this invention.

Figure 4 is a plan view of an end of the long strip, showing several steps involved in the method of this invention.

Figures 1 and 2 show only as much of the die members as it is thought necessary to explain this invention.

The punch press which is employed in carrying out this invention forms no part of the same, as any suitable press may be used and operated in any well-known manner. ing a vertically reciprocable head or punchholder is preferred, as it is easier to feed the long strip to such a press.

The drawings will now be explained.

Figure 2 illustrates the lower or female die member and includes a die block 1 having apertured lugs 2 at'its corners for cooperating with guide rods 3 of the press for accurately positioning the blocks in the press and for properly guiding the punch or male die member in its punching operation.

A die plate 4 of suitable material is secured to the block 1 in any suitable manner. The plate 4: is provided with a plurality of holes 5 and 6 so positioned as to receive the cooperating punches to form corresponding holes in the strip of metal which will thus be fashioned in the laminations when finished. The holes 5 will be in the I pieces and the holes 6 in the E pieces.

The plate 4 is also provided with a cutting edge 7 and projecting rectangular cutting pieces 8 and 9 for cooperating with the punch to cut an E piece from substantially half the width of the strip, with the tongues or legs of the E piece extending transversely of the. strip and in length substantially half of that ofthe width of the strip. The length of the die block 1 is the width of the press, so that the strip is fed from right to left through the die members as illustrated.

Another die plate 10 is suitably secured in the die block 1. This plate has a solid body portion substanially less than half However, for convenience, a press havthe width of the strip and has two lateral cutting projections 11 and 12 similar to the projections 8 and 9 on the plate but extending in the opposite direction.

A punch block 13 is provided with apertured flanges 14L at its corners which engage guide rods 3 for governing the reciprocating motion of the punch as the press is operated, so that the punch will register with the female die member just described. The punch block 13 is provided with a plurality of circular punches 15 for registering with the holes 5 in the die plate A, and another series of punches 18 for registering with the holes 6 in the die plate 4.

An E-shaped punch member 17, shaped to conform to the space in the die member defined by the die plate 1 and the lateral projections 8 and 9, is supported in the punch so as to register with this space when the punch is operated in the cutting or blanking stroke.

Another E-shaped punch member 18 is secured in the punch block arranged to cooperate with the space in the die member defined by the die plate 10 and its associated projections 11 and 12. The punch 18 has a cutting edge 19 for trimming the back side of the E piece fashioned by this punch, which trimming is along one of the guide margins of the strip, and also a. transverse cutting edge 33 to sever the second E piece from the strip.

Figure a illustrates a portion of a strip A from which laminations are formed by the method of this invention. The strip A is slightly greater in width than the width of two E pieces arranged with the legs there of transversely of the strip, the excessive width being just enough to allow narrow waste strips 20 and 21, so that the E pieces will be properly and evenly trimmed on the back sides of the same. The waste strips 20 and 21 also serve for pulling the strip A through the machine when the strip is fed by hand.

The strip A is fed into the machine between the dies illustrated in Figures 1 and 2 from right to left, and the end of the strip brought against the stop 31 so that the section A, which is at the end of the strip, is positioned over the holes 5 and 6 in the die plate l, whereupon, on actuation of the punch, the holes 23 and 2A are punched in the strip. The holes 23 later appear in the I pieces and the holes 24 in the E pieces. The strip is then advanced one step against stop 32, whereupon, on the descent of the punch, the punch plate 17 will cut out an E piece, indicated in dotted lines in Figure 4 in section 7) and represented at 25. This E piece is outwardly cut on all of its margins and its back edge trimmed, leaving the waste strip 21. This E piece 25 so formed falls downwardly through the die block and into a proper receptacle for the same.

The second operation leaves a portion of the strip substantially half the width of the same and in'length equal to the length of an E piece, with two lateral projections 26 and 27 extending transversely of the strip and which remain as integral parts of the strip by reason of the formation of the dies.

The strip is then advanced one step, whereupon, on he next descent of the punch, I pieces 28 and 29 are cut or blanked out, which I pieces include the lateral projections 26 and 27 remaining from step 2 and a similar part of the half of the blank remaining from step 2. In other words, the I pieces are cut in the third operation when the second E piece 30 is formed. The cutting of the I pieces as just described forms the second E piece 30. Simultaneously, this E piece is severed from the strip by the cutting edge 33 of the die member 18 and trimmed on its back edge by the cutting edge 19, leaving the waste strip 20.

The dies illustrated contemplate a threestep process, the first step punching the holes, the second step punching out one E piece and the third step punching out two I pieces and a second E piece and severing the second E piece from the strip, as well as trimming the same on its back edge. The first E piece, formed in the second operation, is also trimmed on its back edge at the time the same is formed, leaving the waste strip 21.

When a strip A is fed to the press for the first time, on the first descent of the punch, the holes are formed in the strip A. The strip is then advanced one step and the first E piece 25 is blanked out and the holes formed in the next successive section of the strip. The strip is then advanced another step and the descent of the punch will punch the holes in the first position or operation, blank out the E piece 25 in the second position leaving the lateral extensions 8 and 9 each substantially half of an I piece and, in the third position, blank out the I pieces 28 and 29, trim the back edge of the E piece 30 and sever the same from the strip, so that, after three operations, continuous feeding of the strip will result in the formation of two E pieces and two I pieces every time the punch descends.

This process in efiect forms two E pieces and two I pieces at every stroke of the press. The first E piece is severed from the strip with the arms or tongues thereof extending transversely of the strip to the median line of the same. The E piece after being severed leaves two lateral extensions 8 and 9 each of which is one half of an I piece. The next operation blanks out the I pieces by completing the same and also rsoaeoe severs the remaining E piece by cutting it from the strip by means of cutting edge 33 of the die member 18 and also trimming it along the back edge by the cutting edge 19 of the die member 18.

The E pieces and I pieces formed in accordance with this invention may be removed from the press in any suitable manner.

The E pieces cut from a strip in accordance with this invention pass downwardly through holes in the bed of the press onto stacking means or into boxes, as may be desired. The I pieces remain on the die members 11 and 12 of the female die member and are preferably blown off by compressed air into a box at the rear side of the press. The end of the strip from which the second E piece and the two I pieces are blanked in the third operation rest 011 the extensions 11 and 12 of the die member 10 with the extensions 8 and 9 of the strip resting on the die member 10 so that when the punch is actuated the E piece severed from the strip in the manner above described passes downwardly through the bed of the press into a box or onto stacking mechanism leaving the I pieces resting on the extensions 11 and 12 and the block 10 which are then blown off by compressed air in the manner stated.

The various punches are, of course, made with due regard to the strains imposed on the strip in the several punching operations, so that no undue strain will be imparted to the strip to fracture the same.

The punch 17 severs acomplete E piece from the strip A, which E piece includes certain of the holes 24 formed in the first operation. The third operation severs a second complete E piece which is trimmed on all sides and which contains certain of the holes 16 formed in the first operation. The third operation also blanks out the two I pieces 28 and 29, each of which has two of the holes 23 in the same.

The strip A may be fed to the press in any manner, but it is contemplated that it be fed by hand from right to left,-in which event the waste strips 20 and 21 will facilitate the drawing of the strip through the press in step by step movement.

Any suitable stop may be provided in the dies for limiting the inward movement of the strip, so that the dies will act on the same properly without undue waste of material. Such a stop is shown at 31 in Figure 1.

This method may, of course, be employed in punching laminations of E and I shape where the strip is fed automatically, as the feed forms no part of this invention.

The laminations made in accordance with this invention are regularly and evenly out clean along all of the edges so that no further work is necessary to be done on the same before assembly into the core, except, perhaps, washing to remove any oil that may be present during the punching operation.

The method of this invention turns out laminations of the character described without any fins on any part of the same, so that these are ready for assembly immediately.

The cutting of the strip through the successive strokes of the punch as above described progresses as the strip A is fed into the dies, but it is to be understood that at every stroke of the punch two complete E pieces and two complete I pieces are completed, of uniform size and shape.

The method of this invention utilizes all of the material of the strip A except the lateral waste strips 20 and 21, which strips are necessary in order that the back edges of the E pieces may be accurately cut. The E pieces and I pieces illustrated in the accompanying drawings all have square corners. It is, of course, within the purview of this invention to illustrate but one form of combination possible to be'made by this method. The dies and punches could, of course, be modified so that the corners could be other than right angle corners, as long as the general contour of the E and I pieces is maintained.

This invention has been described herein more or less precisely as to details, yet it is to be understood that it is not to be limited thereby, as changes may be made in the arrangement and proportion of parts and equivalents may be substituted without departing from the spirit and scope of the invention.

The invention is claimed as follows:

1. The method of making core laminations from a long, relatively narrow strip of material, which consists in cutting an E piece with the legs or tongues thereof extending transversely of the strip to the median line of the strip, then cutting a complementary E piece from the opposite side of the strip, the cutting of the first E piece leaving two extensions integral with the strip each of which is half of an I piece, the cutting of the complete I pieces from the strip being effected when said complementary E piece is cut.

2. The method of making core laminations from a long, relatively narrow strip of material, which consists in cutting an E piece from one side of the strip with the tongues or legs thereof extending transversely of the strip to the median line of the strip, and at the same time cutting a complementary E piece from the other side of the strip ahead of the position of the first E piece in the direction of travel of the strip, the cutting of the first E piece leaving two lateral extensions integral with the strip each of which is half of an I piece, advancing the strip the length of an E-piece, repeating the foregoing operations to efiect cutting of a complementary E-piece, the cutting of the complete I pieces from the strip being eilected when said complementary E piece is cut.

In testimony whereof I have hereunto subscribed my name at Chicago, Cook County,

Illinois.

EDWARD J. DOYLE. 

